1. Field of the Invention
The present invention relates to a variable capacitance module that achieves a capacitance value of a predetermined width and a matching circuit module including the variable capacitance module.
2. Description of the Related Art
In the past, there have been disclosed various kinds of high-frequency modules, each of which transmits and receives, using one antenna, a plurality of communication signals utilizing frequency bands that are different from one another. In such a high-frequency module, for example, if matching is not performed between the antenna and a transmitting and receiving circuit, it is difficult to transmit and receive a communication signal with low loss. If a transmission and reception environment is stable, a capacitance value used for matching is theoretically fixed. However, for example, when the high-frequency module, such as a mobile phone, is easily movable or the orientation thereof can be easily changed, it is difficult to fully perform matching using the fixed capacitance. Therefore, for example, in an RFMEMS element described in Japanese Unexamined Patent Application Publication No. 2003-258502, a MEMS (Micro Electro Mechanical System) element is used as a capacitance element, a ground electrode and a movable electrode are arranged with electrode planes that face each other, and a minute interval is arbitrarily set between the ground electrode and the movable electrode, thereby achieving a desired variable capacitance value necessary for matching.
However, as described above, in the current high-frequency module, since the plurality of communication signals are transmitted and received using one antenna, it is necessary to make the capacitance value variable with respect to each communication signal. Therefore, a necessary variable capacitance range changes, and a capacitance range required for a high-frequency module becomes large. At this time, while a configuration is usually adopted in which a plurality of MEMS elements are provided and connected in parallel, the formation of the plurality of MEMS elements on a same substrate results in the size of the substrate being relatively large. In addition, as illustrated in Japanese Unexamined Patent Application Publication No. 2003-258502, since the MEMS elements are formed by a semiconductor manufacturing process, the substrate size is large, which results in a large cost increase. In addition, when the plurality of MEMS elements are provided on one substrate, a contribution component is generated and a problem occurs in that it is difficult to provide a variable capacitance in a wide frequency band.